Fabrication of Neodymium-Based Superconducting Bulk Materials

We report on Nd123 bulk samples directionally solidified in air prepared with Ba-rich Nd422 doping brown phase by top seeding growth (TSG). By using this technique, we have fabricated single domain pellets up to 3.5 cm of diameter and 1 cm of thickness. The crystallographic alignment and the texture of samples have been investigated by means of polarised light optical microscopy, scanning electron microscope, supplemented by energy dispersive spectroscopy and X-ray diffraction analysis. The resulting microstructures have shown Nd1Ba2Cu3O6+d domains, and Nd4Ba2Cu2O10-d particles' size distribution, depending on the used values of the fabrication process's parameters. In particular, we investigated the influence both of the growth temperature window and of the cooling rate on the growth dynamics of the samples and on the precipitates segregation mechanism was analysed.